Use of il-18 inhibitors for treatment and/or prevention of peripheral vascular diseases

ABSTRACT

The invention relates to the use of an inhibitor of IL-18 in the preparation of a medicament for treatment and/or prevention of peripheral vascular diseases. The invention further relates to the use of an IL-18 inhibitor for prevention of limb amputation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application under 35 U.S.C. §120 ofU.S. application no. 10/508,574, which is a U.S. National Phase EntryApplication under 35 U.S.C. §371 of International ApplicationPCT/EP03/50061, filed Mar. 13, 2003, which claims benefit under 35U.S.C. 119 of the European Patent Application No. 02 100 290.2, filedMar. 22, 2002.

FIELD OF THE INVENTION

The present invention is in the field of vascular diseases. Morespecifically, it relates to the use of an inhibitor of IL-18 for thetreatment and/or prevention of peripheral vascular diseases. Theinvention further relates to the use of an IL-18 inhibitor forprevention of amputation.

BACKGROUND OF THE INVENTION

The cytokine interleukin 18 (IL-18) was initially described as aninterferon-γ (IFN-γ) inducing factor (Nakamura et al., 1989). It is anearly signal in the development of T-lymphocyte helper cell type 1 (TH1)responses. IL-18 acts together with IL-12, IL-2, antigens, mitogens, andpossibly further factors, to induce the production of IFN-γ. IL-18 alsoenhances the production of GM-CSF and IL-2, potentiates anti-CD3 inducedT cell proliferation, and increases Fas-mediated killing of naturalkiller cells.

Mature IL-18 is produced from its precursor by the IL-1β convertingenzyme (ICE, caspase-1).

The IL-18 receptor consists of at least two components, IL-18R alpha andIL-18R beta, co-operating in ligand binding. High- and low-affinitybinding sites for IL-18 were found in murine IL-12 stimulated T cells(Yoshimoto et al., 1998), suggesting a multiple chain receptor complex.The two receptor subunits that have been identified so far, bothbelonging to the IL-1 receptor family (Parnet et al., 1996; Kim et al.,2001). The signal transduction of IL-18 involves activation of NF-κB(DiDonato et al., 1997). The IL-18 receptor complex consists of tworeceptor chains: a ligand-binding chain termed the IL-18Rα chain and asignal-transducing chain termed the IL-18Rβ chain. The IL-18Ralpha chainwas initially isolated as a cell surface protein binding to radiolabeledIL-18; the protein was purified and its amino acid sequence revealedidentity with a previously reported orphan receptor termed the IL-1R-related protein (IL-1 Rrp) (Torigoe et al., 1997).

Recently, a soluble protein having a high affinity for IL-18 has beenisolated from human urine, and the human and mouse cDNAs as well as thehuman gene were cloned (Novick et al., 1999; WO 99/09063). The proteinhas been designated IL-18 binding protein (IL-18BP).

IL-18BP is not the extracellular domain of one of the known IL18receptors, but a secreted, naturally circulating protein. It belongs toa novel family of secreted proteins, further including severalPoxvirus-encoded proteins (Novick et al., 1999). Urinary as well asrecombinant IL-18BP specifically bind IL-18 with a high affinity andmodulate the biological affinity of IL-18.

The IL-18BP gene was localized to the human chromosome 11q13, and noexon coding for a transmembrane domain was found in an 8.3 kb genomicsequence. Four splice variants or isoforms of IL-18BP generated byalternative mRNA splicing have been found in humans so far. They weredesignated IL-18BP a, b, c and d, all sharing the same N-terminus anddiffering in the C-terminus (Novick et al, 1999). These isoforms vary intheir ability to bind IL-18. Of the four, hIL-18BP isoforms a and c areknown to have a neutralizing capacity for IL-18. Human IL-18BP isoformbinds to murine IL-18.

Peripheral vascular disorders may be arterial (occlusive or functional),venous, combined arteriovenous (e.g. arteriovenous fistula), orlymphatic. Occlusive arterial disease includes peripheral arterialocclusion and Buerger's Disease, also called thromboangiitis obliterans.Functional arterial disorders may be vasospastic (Raynaud's phenomenonand disease, acrocyanosis) or vasodilatory (erythromelalgia). They maybe secondary to a local fault in the blood vessels or to disturbances insympathetic nervous system activity, or may accompany organic vasculardisease. Venous diseases include venous thrombosis and varicose veins,combined arteriovenous disorders include arteriovenous fistula, andlymphatic disorders include lymphedema and lipedema.

Peripheral arterial occlusion refers to an occlusion of blood supply tothe extremities, generally by atherosclerotic plaques (atheromas), athrombus, or an embolism.

Peripheral arterial occlusion may result in acute or chronic ischemia.Acute ischemia is caused by a ruptured proximal arteriosclerotic plaque,by acute thrombosis on preexisting atherosclerotic disease, by anembolism from the heart, aorta, or other large vessels, or a dissectedaneurysm. Chronic ischemia is caused by gradual enlargement of anatheromatous plaque.

Sustained elevation of blood homocysteine, by damaging endothelialcells, predisposes to premature atherosclerosis of the aorta and itsbranches, the peripheral arteries, the cerebral arteries, and possiblythe coronary arteries. Although homocysteine levels are usually elevatedin association with other risk factors, they can be modified by diet andvitamin B supplements.

Clinical syndromes of arterial occlusion depend on the vessel involved,the extent of obstruction, how rapidly occlusion progresses, and whethercollateral flow is adequate.

Acute occlusion has a history that includes sudden onset of severe pain,coldness, numbness, and pallor in an extremity. The extremity is coldand pale, and pulses are absent distal to the obstruction. Acuteocclusion may cause severe ischemia manifested by sensory and motor lossand eventually (after 6 to 8 h) tender induration of muscles onpalpation.

In chronic occlusion, the symptoms are related to the insidiousdevelopment of tissue ischemia. The initial symptom is intermittentclaudication. Symptoms of claudication are pain, ache, cramp, or tiredfeeling that occurs on walking. These symptoms are most common in thecalf but may occur in the foot, thigh, hip, or buttocks.

Eventually, ischemic pain may occur at rest, beginning in the mostdistal parts of a limb as a severe, unrelenting pain aggravated byelevation and often preventing sleep.

The level of arterial occlusion and the location of intermittentclaudication closely correlate, e.g. aortoiliac disease frequentlycauses claudication in the buttocks, hips, and calves, and the femoralpulses are reduced or absent. In femoropopliteal disease, claudicationis typically in the calf, and all pulses below the femoral are absent.In patients with small vessel disease (e.g. thromboangiitis obliterans,diabetes mellitus), femoropopliteal pulses may be present but footpulses are absent. Pallor of the involved foot after 1 to 2 min ofelevation, followed by rubor on dependency, helps confirm arterialinsufficiency. Venous filling time on dependency after elevation exceedsthe normal limit of 15 sec. If symptoms of claudication occur with gooddistal pulses, spinal stenosis should be considered in the differentialdiagnosis.

A severely ischemic foot is painful, cold, and often numb. In chroniccases, the skin may be dry and scaly with poor nail and hair growth. Asischemia worsens, ulceration may appear (typically on the toes or heel,occasionally on the leg), especially after local trauma. Edema isusually not present unless the patient has kept the leg in a dependentposition for pain relief, however, a severely ischemic leg may beatrophic. More extensive occlusion may compromise tissue viability,leading to necrosis or gangrene. Ischemia with rubor, pain, and swellingof the foot on dependency may mimic cellulitis or venous insufficiency.Arterial noninvasive tests can clarify the diagnosis.

Among the peripheral vascular diseases, Buerger's Disease(Thromboangiitis Obliterans) is an obliterative disease characterized byinflammatory changes in small and medium-sized arteries and veins.

Buerger's Disease occurs in cigarette smokers, predominantly in men aged20 to 40. Only about 5% of cases occur in women. The frequency ofdiagnosis has decreased drastically in recent years because of betterunderstanding of clinical and angiographic characteristics of thisdisease versus arteriosclerosis obliterans.

Although the cause is unknown, Buerger's Disease has not been documentedin nonsmokers, implicating cigarette smoking as a primary etiologicfactor, perhaps as a delayed type of hypersensitivity or toxic angiitis.Thromboangiitis obliterans may be a reaction to tobacco by persons witha specific phenotype, because of greater prevalence of HLA-A9 and HLA-B5in persons with the disease; or an autoimmune disorder withcell-mediated sensitivity to types I and III human collagen, which areconstituents of blood vessels.

Unlike atherosclerosis, Buerger's Disease does not involve the coronaryarteries.

The disease involves small and medium-sized arteries and, frequently,superficial veins of the extremities in a segmental pattern. Rarely, inadvanced disease, vessels in other parts of the body are affected. Thepathologic appearance is that of a nonsuppurative panarteritis orpanphlebitis with thrombosis of involved vessels. Proliferation ofendothelial cells and infiltration of the intimal layer with lymphocytesoccur in the acute lesion, but the internal elastic lamina is intact.The thrombus becomes organized and later incompletely recanalizes. Themedia is well preserved but may be infiltrated with fibroblasts. Becausethe adventitia usually is more extensively infiltrated with fibroblasts,older lesions show periarterial fibrosis, which may also involve theadjacent vein and nerve.

The symptoms and signs are those of arterial ischemia and of superficialthrombophlebitis. Onset is gradual, starting in the most distal vesselsof the upper and lower extremities and progressing proximally,culminating in distal gangrene. The patient may complain of coldness,numbness, tingling, or burning before there is objective evidence ofdisease. Raynaud's phenomenon is common. Intermittent claudicationoccurs in the involved extremity (usually the arch of the foot or theleg, but rarely the hand, arm, or thigh). Pain is persistent with moresevere ischemia, e.g. in the pregangrenous stage and with ulceration organgrene. Frequently, sympathetic nerve overactivity is manifested bycoldness, excessive sweating, and cyanosis of the involved extremity,probably caused by the severe, persistent pain.

Ischemic ulceration and gangrene, usually of one or more digits, mayoccur early in the disease but not acutely. Noninvasive studies showsevere decreases in blood flow and pressure in affected toes, feet, andfingers. The disease progresses proximally.

Another peripheral vascular disease is peripheral arterial disease, inwhich patients with lower extremity peripheral arterial disease (PAD)may progress to severe, limb-threatening ischemia. Ischemic rest pain,nonhealing ulcerations, and gangrene are all harbingers of pooroutcomes. These patients are at high risk of limb loss. Prompt detectionand evaluation of severe limb ischemia followed by efficientrevascularization are required for limb salvage and preservation ofoverall health.

Chronic critical limb ischemia is the end result of arterial occlusivedisease, most commonly atherosclerosis. In addition to atherosclerosisin association with hypertension, hypercholesterolemia, cigarettesmoking and diabetes less frequent causes of chronic critical limbischemia include Buerger's disease, or thromboangiitis obliterans, andsome forms of arteritis.

The development of chronic critical limb ischemia usually requiresmultiple sites of arterial obstruction that severely reduce blood flowto the tissues. Critical tissue ischemia is manifested clinically asrest pain, non-healing wounds (because of the increased metabolicrequirements of wound healing) or tissue necrosis (gangrene).

Ischemic rest pain is classically described as a burning pain in theball of the foot and toes that is worse at night when the patient is inbed. Ischemic rest pain is located in the foot, where tissue is farthestfrom the heart and distal to the arterial occlusions. Non-healing woundsare usually found in areas of foot trauma caused by improperly fittingshoes or an injury. A wound is generally considered to be nonhealing ifit fails to respond to a four- to 12-week trial of conservative therapysuch as regular dressing changes, avoidance of trauma, treatment ofinfection and debridement of necrotic tissue.

Gangrene is usually found on the toes. It develops when the blood supplyis so low that spontaneous necrosis occurs in the most poorly perfusedtissues.

While carefully designed conservative therapy can benefit many patientswith critical limb ischemia, the severe nature of their disease may leadto consideration of operative intervention. Surgical interventionsinclude revascularization or amputation. If the patient wants to undergorevascularization and is an acceptable operative candidate,arteriography is often performed for further evaluation and planning ofrevascularization. At some centers, magnetic resonance angiography isused as an alternative or supplement to arteriography to minimize therisk of dye exposure. Limb preservation by means of revascularization iscost-effective, leads to a better quality of life for most patients andis associated with lower perioperative morbidity and mortality thanamputation. Limb preservation should be the goal in most patients withchronic critical limb ischemia.

The feasibility of revascularization is determined by the arteriographicfindings as well as the availability of a bypass conduit. Angioplasty orstent placement, or both, is most successful with short, proximallesions, such as those in patients with claudication, but is unlikely tobe the only treatment necessary in the setting of critical limb ischemiabecause of the multilevel nature of the arterial occlusive disease. Theideal bypass conduit is the greater saphenous vein, but other conduitsinclude the lesser saphenous veins, the arm veins or a prostheticconduit. In most surgical series, three-year bypass patency rates ofcalf arteries range from 40 percent for prosthetic bypasses to 85percent for saphenous vein bypasses. In comparison, studies ofconservative therapy have demonstrated a 25 to 49 percent success ratewith nonhealing wounds and a 50 to 80 percent rate of improvement inischemic rest pain.

Primary amputation may be indicated in certain patients, such as thosewith extensive tissue necrosis, life-threatening infection or lesionsnot amenable to revascularization. The decision to monitor the patient'scondition with watchful waiting and conservative management or toperform revascularization or amputation depends on careful assessment ofthe attendant risks and benefits of surgery versus conservativemanagement.

More importantly, it depends on the patient's interpretation of theinvasiveness or appropriateness of the available options. Even patientsunable to walk because of their condition may consider amputationinappropriate, and not all patients are motivated to do the worknecessary for rehabilitation after amputation. If the decision is madeto amputate, the level of amputation should be one that has the greatestlikelihood of healing while giving the patient the maximal chance forfunctional rehabilitation.

Diagnosis of chronic critical limb ischemia involves manifested pain atrest, non-healing wounds and gangrene. Ischemic rest pain is typicallydescribed as a burning pain in the arch or distal foot that occurs whilethe patient is recumbent but is relieved when the patient returns to aposition in which the feet are dependent. Objective hemodynamicparameters that support the diagnosis of critical limb ischemia includean ankle-brachial index of 0.4 or less, an ankle systolic pressure of 50mm Hg or less, or a toe systolic pressure of 30 mm Hg or less.Intervention may include conservative therapy, revascularization oramputation. Progressive gangrene, rapidly enlarging wounds or continuousischemic rest pain can signify a threat to the limb and suggest the needfor revascularization in patients without prohibitive operative risks.Bypass grafts are usually required because of the multilevel and distalnature of the arterial narrowing in critical limb ischemia. Patientswith diabetes are more likely than other patients to have distal diseasethat is less amenable to bypass grafting. Compared with amputation,revascularization is more cost-effective and is associated with betterperioperative morbidity and mortality. Limb preservation should be thegoal in most patients with critical limb ischemia.

At present, the major treatment of peripheral vascular diseases includeinvasive treatment such as angioplasty of even limb amputation.Identification of drugs that stimulate peripheral neovascularizationwithout increasing atherosclerotic plaque progression is of majortherapeutic importance in this medical field.

SUMMARY OF THE INVENTION

The invention is based on the finding that an inhibitor of IL-18stimulates neovascularization after induction of peripheral ischemia inan experimental animal model. Neovascularization occurred in associationwith an activation of VEGF/Akt signaling and was accompanied by anincrease in bone marrow endothelial progenitor cell mobilization anddifferentiation.

On the basis of these results, new therapeutic approaches for treatingor preventing peripheral vascular diseases requiring neo- orrevascularization are provided.

The invention therefore relates to the use of an IL-18 inhibitor fortreatment and/or prevention of peripheral vascular diseases, inparticular of peripheral ischemia.

The invention further relates to the use of an IL-18 inhibitor for themanufacture of a medicament for the treatment and/or prevention ofclaudication and gangrene.

Furthermore, the invention relates to the use of an IL-18 inhibitor forthe manufacture of a medicament for the prevention of amputation, inparticular limb amputation.

The use of an expression vector comprising the coding sequence of aninhibitor of IL-18, as well as the use of an expression vector forinducing and/or enhancing the endogenous production of an inhibitor ofIL-18 in a cell, for treatment or prevention of peripheral vasculardiseases is also within the present invention.

The invention further relates to a method of treatment of peripheralvascular diseases comprising administering to a host in need thereof aneffective inhibiting amount of an IL-18 inhibitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: shows A) Representative microangiography of the right ischemicand left non-ischemic hindlimbs, 3 and 28 days after femoral arteryocclusion in the mouse. B) shows the ischemic/non-ischemic angiographicscore in mice treated with pcDNA3-mIL18BP (IL-18BP) or empty plasmid(Control) for 3 or 28 days. Values are mean±SEM, n=7 per group. **p<0.01versus control mice.

FIG. 2: shows A) Ischemia-induced changes in hindlimb blood flowmonitored in vivo by laser Doppler perfusion imaging in mice treatedwith pcDNA3-mIL18BP (IL-18 BP) or empty plasmid (Control). Incolor-coded images, normal perfusion is depicted in red, a markedreduction in blood flow of ischemic hindlimb is depicted in blue. B)Quantitative evaluation of blood flow expressed as a ratio of blood flowin ischemic limb to that in non-ischemic one. Values are mean±SEM, n=7per group. **p<0.01 versus control mice.

FIG. 3: shows A) Representative western-blot of VEGF protein content inthe non-ischemic and ischemic leg, 28 days after femoral arteryocclusion. B) Quantitative evaluation of VEGF protein levels expressedas a ratio of protein content in ischemic limb to that in non-ischemicone. Values are mean±SEM, n=7 per group. **p<0.01 versus non-ischemiccontrol and tp<0.05 versus ischemic control.

FIG. 4: shows A) Representative western-blot of phospho-Akt proteincontent in the non-ischemic and ischemic leg, 28 days after femoralartery occlusion. B) Quantitative evaluation of phospho-Akt proteinlevels expressed as a ratio of protein content in ischemic limb to thatin non-ischemic one. Values are mean±SEM, n=7 per group. *p<0.05,**p<0.01 versus non-ischemic control and †p<0.05 versus ischemiccontrol.

FIG. 5: A) Representative images of EPCs (endothelial progenitor cells)isolated from bone marrow of mice without femoral artery ligature (Sham)and of mice treated with pcDNA3-mIL18BP (IL-18BP) or empty plasmid(Control). EPCs were characterized as adherent cells withdouble-positive staining for AcLDL-Dil and von-Willebrand factor (vWF)B) Quantification of double-positive cells in mice treated withpcDNA3-mIL18BP or empty plasmid. Values are mean±SEM, n=5 per group.***p<0.001, versus control mice, ††\p<0.001, versus mice without femoralartery ligature (Sham)

DETAILED DESCRIPTION OF THE INVENTION

The present invention is based on the finding that IL-18 inhibitorssignificantly increase post-ischemic angiogenesis after limb ischemiawithout affecting vessel density of the non-ischemic limb in an in vivomurine disease model. Therefore, the invention provides for a newtherapeutic approach to treating or preventing peripheral vasculardiseases requiring enhanced tissue perfusion.

The invention therefore relates to the use of an IL-18 inhibitor for themanufacture of a medicament for the treatment and/or prevention of aperipheral vascular disease.

The term “prevention” within the context of this invention refers notonly to a complete prevention of a certain effect, but also to anypartial or substantial prevention, attenuation, reduction, decrease ordiminishing of the effect before or at early onset of disease.

The term “treatment” within the context of this invention refers to anybeneficial effect on progression of disease, including attenuation,reduction, decrease or diminishing of the pathological development afteronset of disease.

The term “peripheral vascular disease” as used herein refers to diseasesor disorders affecting the arteries, veins, and lymphatics of theextremities. Peripheral vascular disorders may be arterial (occlusive orfunctional), venous, combined arteriovenous (e.g., arteriovenousfistula), or lymphatic. Occlusive arterial disease includes peripheralarterial occlusion and thromboangiitis obliterans. Functional arterialdisorders may be vasospastic (Raynaud's phenomenon and disease,acrocyanosis) or vasodilatory (erythromelalgia). They may also besecondary to a local fault in the blood vessels, or to disturbances insympathetic nervous system activity, or they may accompany organicvascular disease. Venous diseases include venous thrombosis and varicoseveins, combined arteriovenous disorders include arteriovenous fistula,and lymphatic disorders include lymphedema and lipedema.

The term peripheral vascular disease is meant to encompass all medicalindications, diseases, disorders or symptoms described in the“Background of the Invention” above.

The term “inhibitor of IL-18” within the context of this inventionrefers to any molecule modulating IL-18 production and/or action in sucha way that IL-18 production and/or action is attenuated, reduced, orpartially, substantially or completely prevented or blocked.

An inhibitor of production can be any molecule negatively affecting thesynthesis, processing or maturation of IL-18. The inhibitors consideredaccording to the invention can be, for example, suppressors of geneexpression of the interleukin IL-18, antisense mRNAs reducing orpreventing the transcription of the IL-18 mRNA or leading to degradationof the mRNA, proteins impairing correct folding, or partially orsubstantially preventing secretion of IL-18, proteases degrading IL-18,once it has been synthesized, inhibitors of proteases cleaving pro-IL-18in order to generate mature IL-18, such as inhibitors of caspase-1, andthe like.

An inhibitor of IL-18 action can be an IL-18 antagonist, for example.Antagonists can either bind to or sequester the IL-18 molecule itselfwith sufficient affinity and specificity to partially or substantiallyneutralize the IL-18 or IL-18 binding site(s) responsible for IL-18binding to its ligands (like, e.g. to its receptors). An antagonist mayalso inhibit the IL-18 signaling pathway, which is activated within thecells upon binding of IL-18 to its receptor binding.

Inhibitors of IL-18 action may also be soluble IL-18 receptors ormolecules mimicking the receptors, or agents blocking the IL-18receptors, or IL-18 antibodies, such as polyclonal or monoclonalantibodies, or any other agent or molecule preventing the binding ofIL-18 to its targets, thus diminishing or preventing triggering of theintra- or extracellular reactions mediated by IL-18.

In a preferred embodiment of the invention, the peripheral vasculardisease is peripheral arterial disease.

“Peripheral arterial disease” is a disorder involving narrowing of thearteries anywhere from the arms to the aorta and the arteries of thelegs. The onset can be sudden or gradual and generally results inischemia (decreased delivery of oxygen to the area the vessel supplies).

Preferably, in accordance with the present invention, the peripheralarterial disease concerns the lower extremities. Peripheral arterialdisease or occlusion may be chronic or acute. Peripheral arterialdisease is frequently associated with claudication.

Therefore, the present invention further relates to the use of an IL-18inhibitor for treatment and/or prevention of claudication. Claudicationis pain in the leg, in particular in the calf, that comes and goes tocause limping. Claudication typically is felt while walking, andsubsides with rest. It is, therefore, commonly referred to asintermittent claudication. The usually intermittent nature of the painof claudication is due to a temporary inadequate supply of oxygen to themuscles of the leg. The poor oxygen supply is a result of narrowing orocclusion of the arteries that supply the leg with blood. This limitsthe supply of oxygen to the leg muscles and is felt especially when theoxygen requirement of these muscles rises with exercise or walking.

In a preferred embodiment of the invention, the peripheral vasculardisease is Thromboangiitis Obliterans (Buerger's Disease). “Buerger'sDisease” is an obliterative disease characterized by inflammatorychanges in small and medium-sized arteries and veins which often occursin cigarette smokers, predominantly in men aged 20 to 40.

The disease involves small and medium-sized arteries and, frequently,superficial veins of the extremities in a segmental pattern.

In a further preferred embodiment, the peripheral vascular disease isperipheral ischemia, in particular limb ischemia. “Ischemia” is adeficiency in blood supply, generally due to occlusion or trauma ofblood vessels. “Peripheral ischemia” particularly refers to ischemia inthe limbs, i.e. the arms or legs, leading to a deficiency in oxygensupply of the corresponding limb tissue.

In yet a further embodiment of the present invention, the limb ischemiais critical limb ischemia. “Critical limb ischaemia” is a state in whichthe blood supply to the limb is so poor as to threaten its survival. Thepresence of rest pain, ulceration or gangrene indicates critical limbischaemia. Gangrene is the term used to describe dead tissue, and itoften occurs as a result of or in combination with limb ischemia. Anischaemic ulcer is caused by an inadequate blood supply.

Critical limb ischemia, including ganrene or ulcers, requirerevascularization in order to prevent amputation of the limb. Therefore,the present invention also relates to the use of IL-18 inhibitors fortreatment and/or prevention of gangrene and ulcers.

The ultimate consequence of peripheral vascular disease, and inparticular of peripheral ischemia, may be amputation of the affectedlimb, in particular the affected lower limb or foot. Revascularizationwill lead to reperfusion of the affected tissue and thus helps thehealing process.

Therefore, the invention further relates to the use of an IL-18inhibitor for the manufacture of a medicament for the prevention ofamputation of the limbs, in particular of a lower limb, foot or toe(s).

In a preferred embodiment of the present invention, the inhibitor ofIL-18 is selected from inhibitors of caspase-1 (ICE), antibodiesdirected against IL-18, antibodies directed against any of the IL-18receptor subunits, inhibitors of the IL-18 signaling pathway,antagonists of IL-18 which compete with IL-18 and block the IL-18receptor, and IL-18 binding proteins, isoforms, muteins, fused proteins,functional derivatives, active fractions or circularly permutatedderivatives thereof inhibiting the biological activity of IL-18.

The term “IL-18 binding proteins” is used herein synonymously with“IL-18 binding protein” or “IL18BP”. It comprises IL-18 binding proteinsas defined in WO 99/09063 or in Novick et al., 1999, including splicevariants and/or isoforms of IL-18 binding proteins, as defined in Kim etal., 2000, which bind to IL-18. In particular, human isoforms a and c ofIL-18BP are useful in accordance with the presence invention. Theproteins useful according to the present invention may be glycosylatedor non-glycosylated, they may be derived from natural sources, such asurine, or they may preferably be produced recombinantly. Recombinantexpression may be carried out in prokaryotic expression systems like E.coli, or in eukaryotic, and preferably in mammalian, expression systems.A cell line that is particularly well suited for expression of mammalianproteins is the Chinese Hamster Ovary (CHO) cell line.

As used herein the term “muteins” refers to analogs of an IL-18BP, oranalogs of a viral IL-18BP, in which one or more of the amino acidresidues of a natural IL-18BP or viral IL-18BP are replaced by differentamino acid residues, or are deleted, or one or more amino acid residuesare added to the natural sequence of an IL-18BP, or a viral IL-18BP,without changing considerably the activity of the resulting products ascompared with the wild type IL-18BP or viral IL-18BP. These muteins areprepared by known synthesis and/or by site-directed mutagenesistechniques, or any other known technique suitable therefor.

Muteins in accordance with the present invention include proteinsencoded by a nucleic acid, such as DNA or RNA, which hybridizes to DNAor RNA, which encodes an IL-18BP or encodes a viral IL-18BP, asdescribed in WO 99/09063, under stringent conditions. The term“stringent conditions” refers to hybridization and subsequent washingconditions, which those of ordinary skill in the art conventionallyrefer to as “stringent”. See Ausubel et al., Current Protocols inMolecular Biology, supra, Interscience, N.Y., §§6.3 and 6.4 (1987,1992), and Sambrook et al., supra. Without limitation, examples ofstringent conditions include washing conditions 12-20° C. below thecalculated Tm of the hybrid under study in, e.g., 2×SSC and 0.5% SDS for5 minutes, 2×SSC and 0.1% SDS for 15 minutes; 0.1×SSC and 0.5% SDS at37° C. for 30-60 minutes and then, a 0.1×SSC and 0.5% SDS at 68° C. for30-60 minutes. Those of ordinary skill in this art understand thatstringency conditions also depend on the length of the DNA sequences,oligonucleotide probes (such as 10-40 bases) or mixed oligonucleotideprobes. If mixed probes are used, it is preferable to use tetramethylammonium chloride (TMAC) instead of SSC. See Ausubel, supra.

Any such mutein preferably has a sequence of amino acids sufficientlyduplicative of that of an IL-18BP, or sufficiently duplicative of aviral IL-18BP, such as to have an activity comparable to IL-18BP. Oneactivity of IL-18BP is its capability of binding IL-18. As long as themutein has substantial binding activity to IL-18, it can be used in thepurification of IL-18, such as by means of affinity chromatography, andthus can be considered to have substantially similar activity toIL-18BP. Thus, it can be determined whether any given mutein hassubstantially the same activity as IL-18BP by means of routineexperimentation comprising subjecting such a mutein, e.g., to a simplesandwich competition assay to determine whether or not it binds to anappropriately labeled IL-18, such as radioimmunoassay or ELISA assay.

In a preferred embodiment, any such mutein has at least 40% identity orhomology with the sequence of either an IL-18BP or a virally-encodedIL-18BP homologue, as defined in WO 99/09063. More preferably, it has atleast 50%, at least 60%, at least 70%, at least 80% or, most preferably,at least 90% identity or homology thereto.

Muteins of IL-18BP polypeptides or muteins of viral IL-18BPs, which canbe used in accordance with the present invention, or nucleic acid codingtherefor, include a finite set of substantially corresponding sequencesas substitution peptides or polynucleotides which can be routinelyobtained by one of ordinary skill in the art, without undueexperimentation, based on the teachings and guidance presented herein.

Preferred changes for muteins in accordance with the present inventionare what are known as “conservative” substitutions. Conservative aminoacid substitutions of IL-18BP polypeptides or proteins or viralIL-18BPs, may include synonymous amino acids within a group which havesufficiently similar physicochemical properties that substitutionbetween members of the group will preserve the biological function ofthe molecule (Grantham, 1974). It is clear that insertions and deletionsof amino acids may also be made in the above-defined sequences withoutaltering their function, particularly if the insertions or deletionsonly involve a few amino acids, e.g., under thirty, and preferably underten, and do not remove or displace amino acids which are critical to afunctional conformation, e.g., cysteine residues. Proteins and muteinsproduced by such deletions and/or insertions come within the purview ofthe present invention.

Preferably, the synonymous amino acid groups are those defined inTable 1. More preferably, the synonymous amino acid groups are thosedefined in Table 2; and most preferably the synonymous amino acid groupsare those defined in Table 3.

TABLE 1 Preferred Groups of Synonymous Amino Acids Amino Acid SynonymousGroup Ser Ser, Thr, Gly, Asn Arg Arg, Gln, Lys, Glu, His Leu Ile, Phe,Tyr, Met, Val, Leu Pro Gly, Ala, Thr, Pro Thr Pro, Ser, Ala, Gly, His,Gln, Thr Ala Gly, Thr, Pro, Ala Val Met, Tyr, Phe, Ile, Leu, Val GlyAla, Thr, Pro, Ser, Gly Ile Met, Tyr, Phe, Val, Leu, Ile Phe Trp, Met,Tyr, Ile, Val, Leu, Phe Tyr Trp, Met, Phe, Ile, Val, Leu, Tyr Cys Ser,Thr, Cys His Glu, Lys, Gln, Thr, Arg, His Gln Glu, Lys, Asn, His, Thr,Arg, Gln Asn Gln, Asp, Ser, Asn Lys Glu, Gln, His, Arg, Lys Asp Glu,Asn, Asp Glu Asp, Lys, Asn, Gln, His, Arg, Glu Met Phe, Ile, Val, Leu,Met Trp Trp

TABLE 2 More Preferred Groups of Synonymous Amino Acids Amino AcidSynonymous Group Ser Ser Arg His, Lys, Arg Leu Leu, Ile, Phe, Met ProAla, Pro Thr Thr Ala Pro, Ala Val Val, Met, Ile Gly Gly Ile Ile, Met,Phe, Val, Leu Phe Met, Tyr, Ile, Leu, Phe Tyr Phe, Tyr Cys Cys, Ser HisHis, Gln, Arg Gln Glu, Gln, His Asn Asp, Asn Lys Lys, Arg Asp Asp, AsnGlu Glu, Gln Met Met, Phe, Ile, Val, Leu Trp Trp

TABLE 3 Most Preferred Groups of Synonymous Amino Acids Amino AcidSynonymous Group Ser Ser Arg Arg Leu Leu, Ile, Met Pro Pro Thr Thr AlaAla Val Val Gly Gly Ile Ile, Met, Leu Phe Phe Tyr Tyr Cys Cys, Ser HisHis Gln Gln Asn Asn Lys Lys Asp Asp Glu Glu Met Met, Ile, Leu Trp Met

Examples of production of amino acid substitutions in proteins which canbe used for obtaining muteins of IL-18BP polypeptides or proteins, ormuteins of viral IL-18BPs, for use in the present invention include anyknown method steps, such as presented in U.S. Pat. Nos. 4,959,314,4,588,585 and 4,737,462, to Mark et al; 5,116,943 to Koths et al.,4,965,195 to Namen et al; 4,879,111 to Chong et al; and 5,017,691 to Leeet al; and lysine substituted proteins presented in U.S. Pat. No.4,904,584 (Shaw et al).

The term “fused protein” refers to a polypeptide comprising an IL-18BP,or a viral IL-18BP, or a mutein or fragment thereof, fused with anotherprotein, which, e.g., has an extended residence time in body fluids. AnIL-18BP or a viral IL-18BP, may thus be fused to another protein,polypeptide or the like, e.g., an immunoglobulin or a fragment thereof.

“Functional derivatives” as used herein cover derivatives of IL-18BPs ora viral IL-18BP, and their muteins and fused proteins, which may beprepared from the functional groups which occur as side chains on theresidues or the N- or C-terminal groups, by means known in the art, andare included in the invention as long as they remain pharmaceuticallyacceptable, i.e. they do not destroy the activity of the protein whichis substantially similar to the activity of IL-18BP, or viral IL-18BPs,and do not confer toxic properties on compositions containing it.

These derivatives may, for example, include polyethylene glycolside-chains, which may mask antigenic sites and extend the residence ofan IL-18BP or a viral IL-18BP in body fluids. Other derivatives includealiphatic esters of the carboxyl groups, amides of the carboxyl groupsby reaction with ammonia or with primary or secondary amines, N-acylderivatives of free amino groups of the amino acid residues formed withacyl moieties (e.g. alkanoyl or carbocyclic aroyl groups) or O-acylderivatives of free hydroxyl groups (for example that of seryl orthreonyl residues) formed with acyl moieties.

As “active fractions” of an IL-18BP, or a viral IL-18BP, muteins andfused proteins, the present invention covers any fragment or precursorsof the polypeptide chain of the protein molecule alone or together withassociated molecules or residues linked thereto, e.g., sugar orphosphate residues, or aggregates of the protein molecule or the sugarresidues by themselves, provided said fraction has substantially similaractivity to IL-18BP.

In a further preferred embodiment of the invention, the inhibitor ofIL-18 is antibody directed against IL-18 or its receptor, the IL-18R.Antibodies directed to any of the IL-18R subunits, called IL-18Rα and β,may be used in accordance with the present invention.

The antibodies according to the invention may be polyclonal ormonoclonal, chimeric, humanized, or even fully human. Recombinantantibodies and fragments thereof are characterized by high affinitybinding to IL-18 or IL-18R in vivo and low toxicity. The antibodieswhich can be used in the invention are characterized by their ability totreat patients for a period sufficient to have good to excellentregression or alleviation of the pathogenic condition or any symptom orgroup of symptoms related to a pathogenic condition, and a low toxicity.

Neutralizing antibodies are readily raised in animals such as rabbits,goat or mice by immunization with IL-18 or IL-18Rα or β. Immunized miceare particularly useful for providing sources of B cells for themanufacture of hybridomas, which in turn are cultured to produce largequantities of anti-IL-18 monoclonal antibodies.

Chimeric antibodies are immunoglobulin molecules characterized by two ormore segments or portions derived from different animal species.Generally, the variable region of the chimeric antibody is derived froma non-human mammalian antibody, such as murine monoclonal antibody, andthe immunoglobulin constant region is derived from a humanimmunoglobulin molecule. Preferably, both regions and the combinationhave low immunogenicity as routinely determined (Elliott et al., 1994).Humanized antibodies are immunoglobulin molecules created by geneticengineering techniques in which the murine constant regions are replacedwith human counterparts while retaining the murine antigen bindingregions. The resulting mouse-human chimeric antibody preferably havereduced immunogenicity and improved pharmacokinetics in humans (Knightet al., 1993).

Thus, in a further preferred embodiment, IL-18 or IL-18R antibody is ahumanized antibody. Preferred examples of humanized anti-IL-18antibodies are described in the European Patent Application EP 0 974600, for example.

In yet a further preferred embodiment, the antibody is fully human. Thetechnology for producing human antibodies is described in detail e.g. inWO00/76310, WO99/53049, U.S. Pat. No. 6,162,963 or AU5336100.

One method for the preparation of fully human antibodies consist of“humanization” of the mouse humoral immune system, i.e. production ofmouse strains able to produce human Ig (Xenomice), by the introductionof human immunoglobulin (Ig) loci into mice in which the endogenous Iggenes have been inactivated. The Ig loci are complex in terms of boththeir physical structure and the gene rearrangement and expressionprocesses required to ultimately produce a broad immune response.Antibody diversity is primarily generated by combinatorial rearrangementbetween different V, D, and J genes present in the Ig loci. These locialso contain the interspersed regulatory elements, which controlantibody expression, allelic exclusion, class switching and affinitymaturation. Introduction of un-rearranged human Ig transgenes into micehas demonstrated that the mouse recombination machinery is compatiblewith human genes. Furthermore, hybridomas secreting antigen specifichu-mAbs of various isotypes can be obtained by Xenomice immunisationwith antigen.

Fully human antibodies and methods for their production are known in theart (Mendez et at (1997); Buggemann et at (1991); Tomizuka et al.,(2000) Patent WO 98/24893).

In a highly preferred embodiment of the present invention, the inhibitorof IL-18 is an IL-18BP, or an isoform, a mutein, fused protein,functional derivative, active fraction or circularly permutatedderivative thereof. These isoforms, muteins, fused proteins orfunctional derivatives retain the biological activity of IL-18BP, inparticular the binding to IL-18, and preferably have essentially atleast an activity similar to IL-18BP. Ideally, such proteins have anenhanced biological activity as compared to unmodified IL-18BP.Preferred active fractions have an activity which is better than theactivity of IL-18BP, or which have further advantages, like a betterstability or a lower toxicity or immunogenicity, or they are easier toproduce in large quantities, or easier to purify.

The sequences of IL-18BP and its splice variants/isoforms can be takenfrom WO99/09063 or from Novick et al., 1999, as well as from Kim et al.,2000.

Functional derivatives of IL-18BP may be conjugated to polymers in orderto improve the properties of the protein, such as the stability,half-life, bioavailability, tolerance by the human body, orimmunogenicity. To achieve this goal, IL18-BP may be linked e.g. toPolyethlyenglycol (PEG). PEGylation may be carried out by known methods,described in WO 92/13095, for example.

Therefore, in a preferred embodiment of the present invention, theinhibitors of IL-18, and in particular the IL-18BP is PEGylated.

In a further preferred embodiment of the invention, the inhibitor ofIL-18 comprises an immunoglobulin fusion, i.e. the inhibitor of IL-18 isa fused protein comprising all or part of an IL-18 binding protein,which is fused to all or a portion of an immunoglobulin. Methods formaking immunoglobulin fusion proteins are well known in the art, such asthe ones described in WO 01/03737, for example. The person skilled inthe art will understand that the resulting fusion protein of theinvention retains the biological activity of IL-18BP, in particular thebinding to IL-18. The fusion may be direct, or via a short linkerpeptide which can be as short as 1 to 3 amino acid residues in length orlonger, for example, 13 to 20 amino acid residues in length. Said linkermay be a tripeptide of the sequence E-F-M (Glu-Phe-Met), for example, ora 13-amino acid linker sequence comprisingGlu-Phe-Gly-Ala-Gly-Leu-Val-Leu-Gly-Gly-Gln-Phe-Met introduced betweenthe IL-18BP sequence and the immunoglobulin sequence. The resultingfusion protein has improved properties, such as an extended residencetime in body fluids (half-life), increased specific activity, increasedexpression level, or the purification of the fusion protein isfacilitated.

In a preferred embodiment, IL-18BP is fused to the constant region of anIg molecule. Preferably, it is fused to heavy chain regions, like theCH2 and CH3 domains of human IgG1 or IgG2, for example. The generationof specific fusion proteins comprising IL-18BP and a portion of animmunoglobulin are described in example 11 of WO 99/09063, for example.Other isoforms of Ig molecules are also suitable for the generation offusion proteins according to the present invention, such as isoformsIgG₂ or IgG₄, or other Ig classes, like IgM or IgA, for example. Fusionproteins may be monomeric or multimeric, hetero- or homomultimeric.

In yet a further embodiment of the invention, an inhibitor of IL-18 isused in combination with one or more other molecules active in theclinical conditions of the invention, such as vasodilators, Ca-blockers,aspirin, beta-blockers or the like. TNF antagonists may also be used incombination with an IL-18 inhibitor in accordance with the presentinvention, for example. TNF antagonists exert their activity in severalways. First, antagonists can bind to or sequester the TNF moleculeitself with sufficient affinity and specificity to partially orsubstantially neutralize the TNF epitope or epitopes responsible for TNFreceptor binding (hereinafter termed “sequestering antagonists”). Asequestering antagonist may be, for example, an antibody directedagainst TNF.

Alternatively, TNF antagonists can inhibit the TNF signaling pathwayactivated by the cell surface receptor after TNF binding (hereinaftertermed “signaling antagonists”). Both groups of antagonists are useful,either alone or together, in combination with an IL-18 inhibitor, in thetherapy or prevention of peripheral vascular disease.

TNF antagonists are easily identified and evaluated by routine screeningof candidates for their effect on the activity of native TNF onsusceptible cell lines in vitro, for example human B cells, in which TNFcauses proliferation and immunoglobulin secretion. The assay containsTNF formulation at varying dilutions of candidate antagonist, e.g. from0.1 to 100 times the molar amount of TNF used in the assay, and controlswith no TNF or only antagonist (Tucci et al., 1992).

Sequestering antagonists are the preferred TNF antagonists to be usedaccording to the present invention. Amongst sequestering antagonists,those polypeptides that bind TNF with high affinity and possess lowimmunogenicity are preferred. Soluble TNF receptor molecules andneutralizing antibodies to TNF are particularly preferred. For example,soluble TNF-RI and TNF-RII are useful in the present invention.Truncated forms of these receptors, comprising the extracellular domainsof the receptors or functional portions thereof, are more particularlypreferred antagonists according to the present invention. Truncatedsoluble TNF type-I and type-II receptors are described in EP914431, forexample.

Truncated forms of the TNF receptors are soluble and have been detectedin urine and serum as 30 kDa and 40 kDa TNF inhibitory binding proteins,which are called TBPI and TBPII, respectively (Engelmann et al., 1990).The simultaneous, sequential, or separate use of the IL-18 inhibitorwith the TNF antagonist is preferred according to the invention.

In a further preferred embodiment, human soluble TNF-R1 (TBPI) is theTNF antagonist to be used according to the invention. The natural andrecombinant soluble TNF receptor molecules and methods of theirproduction have been described in the European Patents EP 308 378, EP398 327 and EP 433 900.

Derivatives, fragments, regions and biologically active portions of thereceptor molecules functionally resemble the receptor molecules that canalso be used in the present invention. Such biologically activeequivalent or derivative of the receptor molecule refers to the portionof the polypeptide, or of the sequence encoding the receptor molecule,that is of sufficient size and able to bind TNF with such an affinitythat the interaction with the membrane-bound TNF receptor is inhibitedor blocked.

The IL-18 inhibitor can be used simultaneously, sequentially orseparately with the TNF inhibitor.

In a further preferred embodiment of the present invention, theinhibitor of IL-18 is used in an amount of about 0.01 to 100 mg/kg orabout 1 to 10 mg/kg or 2 to 5 mg/kg.

The IL-18 inhibitor according to the invention is preferablyadministered systemically, and preferably subcutaneously orintramuscularly. It may be administered daily, or every other day.Sustained release formulations make it possible to administer lessoften, such as once a week, for instance.

The invention further relates to the use of an expression vectorcomprising the coding sequence of an inhibitor of IL-18 in thepreparation of a medicament for the prevention and/or treatment of aperipheral vascular disease. Thus, a gene therapy approach is consideredin order to deliver the IL-18 inhibitor to the site where it isrequired. In order to treat and/or prevent a peripheral vasculardisease, the gene therapy vector comprising the sequence of an inhibitorof IL-18 may be injected directly into the diseased tissue, for example,thus avoiding problems involved in systemic administration of genetherapy vectors, like dilution of the vectors, reaching and targeting ofthe target cells or tissues, and of side effects.

The use of a vector for inducing and/or enhancing the endogenousproduction of an inhibitor of IL-18 in a cell normally silent forexpression of an IL-18 inhibitor, or which expresses amounts of theinhibitor which are not sufficient, are also contemplated according tothe invention. The vector may comprise regulatory sequences functionalin the cells desired to express the inhibitor or IL-18. Such regulatorysequences may be promoters or enhancers, for example. The regulatorysequence may then be introduced into the right locus of the genome byhomologous recombination, thus operably linking the regulatory sequencewith the gene, the expression of which is required to be induced orenhanced. The technology is usually referred to as “Endogenous GeneActivation” (EGA), and it is described e.g. in WO 91/09955.

It will be understood by the person skilled in the art that it is alsopossible to shut down IL-18 expression directly, without using aninhibitor of IL-18, with the same technique. To do that, a negativeregulation element, like e.g. a silencing element, may be introducedinto the gene locus of IL-18, thus leading to down-regulation orprevention of IL-18 expression. The person skilled in the art willunderstand that such down-regulation or silencing of IL-18 expressionhas the same effect as the use of an IL-18 inhibitor in order to preventand/or treat disease.

The invention further relates to the use of a cell that has beengenetically modified to produce an inhibitor of IL-18 in the manufactureof a medicament for the treatment and/or prevention of a peripheralvascular disease.

The IL-18 inhibitor to be used in accordance with the present inventionmay be preferable administered as a pharmaceutical composition,optionally in combination with a therapeutically effective amount of aTNF inhibitor or another drug active in treatment or prevention of aperipheral vascular disease.

IL-18BP and its isoforms, muteins, fused proteins, functionalderivatives, active fractions or circularly permutated derivatives asdescribed above are the preferred active ingredients of thepharmaceutical compositions.

The definition of “pharmaceutically acceptable” is meant to encompassany carrier, which does not interfere with effectiveness of thebiological activity of the active ingredient and that is not toxic tothe host to which it is administered. For example, for parenteraladministration, the active protein(s) may be formulated in a unit dosageform for injection in vehicles such as saline, dextrose solution, serumalbumin and Ringer's solution.

The active ingredients of the pharmaceutical composition according tothe invention can be administered to an individual in a variety of ways.The routes of administration include intradermal, transdermal (e.g. inslow release formulations), intramuscular, intraperitoneal, intravenous,subcutaneous, oral, intracranial, epidural, topical, and intranasalroutes. Any other therapeutically efficacious route of administrationcan be used, for example absorption through epithelial or endothelialtissues or by gene therapy wherein a DNA molecule encoding the activeagent is administered to the patient (e.g. via a vector), which causesthe active agent to be expressed and secreted in vivo. In addition, theprotein(s) according to the invention can be administered together withother components of biologically active agents such as pharmaceuticallyacceptable surfactants, excipients, carriers, diluents and vehicles.

For parenteral (e.g. intravenous, subcutaneous, intramuscular)administration, the active protein(s) can be formulated as a solution,suspension, emulsion or lyophilized powder in association with apharmaceutically acceptable parenteral vehicle (e.g. water, saline,dextrose solution) and additives that maintain isotonicity (e.g.mannitol) or chemical stability (e.g. preservatives and buffers). Theformulation is sterilized by commonly used techniques.

The bioavailability of the active protein(s) according to the inventioncan also be ameliorated by using conjugation procedures which increasethe half-life of the molecule in the human body, for example linking themolecule to polyethylenglycol, as described in the PCT PatentApplication WO 92/13095.

The therapeutically effective amounts of the active protein(s) will be afunction of many variables, including the type of antagonist, theaffinity of the antagonist for IL-18, any residual cytotoxic activityexhibited by the antagonists, the route of administration, the clinicalcondition of the patient (including the desirability of maintaining anon-toxic level of endogenous IL-18 activity).

A “therapeutically effective amount” is such that when administered, theIL-18 inhibitor results in inhibition of the biological activity ofIL-18. The dosage administered, as single or multiple doses, to anindividual will vary depending upon a variety of factors, includingIL-18 inhibitor pharmacokinetic properties, the route of administration,patient conditions and characteristics (sex, age, body weight, health,size), extent of symptoms, concurrent treatments, frequency of treatmentand the effect desired. Adjustment and manipulation of establisheddosage ranges are well within the ability of those skilled in the art,as well as in vitro and in vivo methods of determining the inhibition ofIL-18 in an individual.

According to the invention, the inhibitor of IL-18 is used in an amountof about 0.001 to 100 mg/kg or about 0.01 to 10 mg/kg or body weight, orabout 0.1 to 5 mg/kg of body weight or about 1 to 3 mg/kg of body weightor about 2 mg/kg of body weight.

The route of administration which is preferred according to theinvention is administration by subcutaneous route. Intramuscularadministration is further preferred according to the invention. In orderto administer the IL-18 inhibitor directly to the place of its action,it is also preferred to administer it topically.

In further preferred embodiments, the inhibitor of IL-18 is administereddaily or every other day.

The daily doses are usually given in divided doses or in sustainedrelease form effective to obtain the desired results. Second orsubsequent administrations can be performed at a dosage which is thesame, less than or greater than the initial or previous doseadministered to the individual. A second or subsequent administrationcan be administered during or prior to onset of the disease.

According to the invention, the IL-18 inhibitor can be administeredprophylactically or therapeutically to an individual prior to,simultaneously or sequentially with other therapeutic regimens or agents(e.g. multiple drug regimens), in a therapeutically effective amount, inparticular with a TNF inhibitor and/or another vascularprotective agent.Active agents that are administered simultaneously with othertherapeutic agents can be administered in the same or differentcompositions.

The invention further relates to a method for the preparation of apharmaceutical composition comprising admixing an effective amount of anIL-18 inhibitor and/or a TNF antagonist with a pharmaceuticallyacceptable carrier.

The invention further relates to a method of treatment of a peripheralvascular disease, comprising administering a pharmaceutically effectiveamount of an IL-18 inhibitor, optionally in combination with apharmaceutically effective amount of an TNF antagonist, to a patient inneed thereof.

Having now fully described this invention, it will be appreciated bythose skilled in the art that the same can be performed within a widerange of equivalent parameters, concentrations and conditions withoutdeparting from the spirit and scope of the invention and without undueexperimentation.

While this invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodifications. This application is intended to cover any variations,uses or adaptations of the invention following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come within known or customary practice within theart to which the invention pertains and as may be applied to theessential features hereinbefore set forth as follows in the scope of theappended claims.

All references cited herein, including journal articles or abstracts,published or unpublished U.S. or foreign patent application, issued U.S.or foreign patents or any other references, are entirely incorporated byreference herein, including all data, tables, figures and text presentedin the cited references. Additionally, the entire contents of thereferences cited within the references cited herein are also entirelyincorporated by reference.

Reference to known method steps, conventional methods steps, knownmethods or conventional methods is not any way an admission that anyaspect, description or embodiment of the present invention is disclosed,taught or suggested in the relevant art.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingknowledge within the skill of the art (including the contents of thereferences cited herein), readily modify and/or adapt for variousapplication such specific embodiments, without undue experimentation,without departing from the general concept of the present invention.Therefore, such adaptations and modifications are intended to be withinthe meaning an range of equivalents of the disclosed embodiments, basedon the teaching and guidance presented herein. It is to be understoodthat the phraseology or terminology herein is for the purpose ofdescription and not of limitation, such that the terminology orphraseology of the present specification is to be interpreted by theskilled artisan in light of the teachings and guidance presented herein,in combination with the knowledge of one of ordinary skill in the art.

EXAMPLES Example 1 Inhibition of IL-18 Reduces Peripheral Ischemia

Methods:

Introduction of Hindlimb Ischema

Male C57BL/6J mice (Iffa Creddo, Lyon, France) underwent surgery toinduce unilateral hindlimb ischemia. Animals were anesthetized byisoflurane inhalation. The ligature was performed on the right femoralartery, 0.5 cm proximal to the bifurcation of the saphenous andpopliteal arteries. Mice (7 animals per group) were then housed underspecific pathogen-free conditions for 3 or 28 days. To examine the roleof IL-18BP in ischemia-induced angiogenesis, a group of mice wasinjected with 60 μg of the murine IL-18BP expression plasmid,pcDNA3-mIL18BP in both tibial cranial muscles, as previously described(Mallat et at, 2001). The control mice were injected with the samedosage of the control empty plasmid. Transcutaneous electric pulses (8square wave electric pulses of 200 V/cm, 20 ms duration at 2 Hz) weredelivered by a PS-15 electropulsator (Genetronics) using two stainlesssteel plate electrodes, placed 4.2 to 5.3 mm apart, at each side of theleg. This strategy was used because it was have previously shown that itincreases IL-18BP plasma levels, decreases plasma IL-18 activity andinhibits atherosclerotic plaque development and progression (Mallat etal., 2001).

Quantification of Angiogenesis

Microangiography

Vessel density was evaluated by high definition microangiography at theend of the treatment period, as previously described (Silvestre et at,2000; Silvestre et al., 2001). Briefly, mice were anesthetized(isoflurane inhalation) and a contrast medium (Barium sulfate, 1 g/ml)was injected through a catheter introduced into the abdominal aorta.Images (3 per animals) acquired by a digital X-ray transducer wereassembled in order to obtain a complete view of the hindlimbs. Thevessel density was expressed as a percentage of pixels per imageoccupied by vessels in the quantification area. A quantification zonewas delineated by the place of the ligature on the femoral artery, theknee, the edge of the femur and the external limit of the leg.

Capillary Density

Microangiographic analysis was completed by assessment of capillarydensities in ischemic and non-ischemic muscles, as previously described(Silvestre et al., 2000; Silvestre et al., 2001). Frozen tissu sections(7 μm) were incubated with rat monoclonal antibody directed against CD31(20 μg/ml, Pharmingen) to identify capillaries. Immunostains werevisualized by using avidin-biotin horseradish peroxydase visualizationsystems (Vectastain ABC kit elite, Vector Laboratories). Capillarydensities were calculated in randomly chosen fields of a definite area,using Histolab software (Microvision).

Laser Doppler Perfusion Imaging

To provide functional evidence for ischemia-induced changes invascularization, Laser Doppler Perfusion Imaging experiments wereperformed, as previously described (Silvestre et al., 2000; Silvestre etal., 2001). Briefly, excess hairs were removed by depilatory cream fromthe limb before imaging, and mice were placed on a heating plate at 37°C. to minimize temperature variation. Nevertheless, to account forvariables, including ambient light and temperature, calculated perfusionwas expressed as a ratio of ischemic to non-ischemic leg.

Statistical Analysis

Results are expressed as mean±SEM. One way analysis of variance ANOVAwas used to compare each parameter. Post hoc Bonferonni's t testcomparisons were then performed to identify which group differencesaccount for the significant overall ANOVA. A value of p<0.05 wasconsidered as statistically significant.

Results:

Microangiography

At day 3, ischemic/non-ichemic leg angiographic score ratios wereunaffected, in either group (FIG. 1). In contrast, at day 28,angiographic score showed 1.6-fold increase in mice treated with IL-18BPcompared to controls (p<0.01).

Capillary Density

Microangiographic data were confirmed by capillary density analysisafter CD31 staining. At day 28, capillary density of the ischemic leg ofcontrol mice was lower than that of the nonischemic leg (415±31 versus688±42 vessels/mm², p<0.01). However, capillary density of the ischemicleg of IL-18BP-treated mice was significantly higher (1.4-fold increase)than that of control mice (588±48 versus 415±31 vessels/mm²,respectively, p=0.01) and did not differ from the level observed in thenonischemic leg.

Laser Doppler Perfusion Imaging

Microangiographic and capillary density measurements were associatedwith changes in blood perfusion. Hindlimb blood flow recovery occurredin both treated and untreated mice. However, in IL-18BP treated mice, agreater increase in blood flow (foot perfusion) was evident by day 28compared to control animals (1.5-fold, p<0.01, FIG. 2).

Example 2 Regulation of VEGF, Phospho-Akt and eNOS Protein Level

Method:

VEGF, phospho-Akt and eNOS (endothelial nitric oxide synthase protein)expression was determined by western-blot in ischemic and non-ischemiclegs, as previously described (Silvestre et al., 2000; Silvestre et al.,2001).

Results:

VEGF. At day 3, no changes in VEGF protein level were observed betweenthe ischemic and non-ischemic legs, in either group. At day 28, incontrol mice, VEGF protein content tended to increase in the ischemicleg when compared with the non-ischemic one, but this did not reachstatistical significance. In contrast, VEGF protein level of theischemic leg was markedly upregulated by 120% in IL-18BP-treated micecompared to controls (p<0.05) (FIG. 3).

Phospho-Akt. At day 3, phospho-Akt protein level was unchanged inischemic and non-ischemic hindlimbs whatever the treatment. At day 28,in control mice, phospho-Akt protein content was increased by 60% inischemic hindlimb over that of non ischemic one (p<0.01). This increasein phospho-Akt content of the ischemic leg doubled in mice treated withIL-18BP (110% increase, p<0.05 as compared with the increase in theischemic leg of control mice) (FIG. 4).

eNOS. At day 3, eNOS protein content was unaffected in ischemic (107±8%versus 103±24%) and non ischemic legs (100±12% versus 94±21%) forcontrol and IL-18BP-treated animals, respectively. At day 28, in controlmice, eNOS levels were raised by 55% in the ischemic leg in reference tothe non-ischemic one (155±8% versus 100±11%, respectively, p<0.05). Suchan increase was unaffected by IL-18BP treatment (160±12%, P=0.61 versusischemic control).

Example 3 Effect of IL-18BP on EPCs (Endothelial Progenitor Cells)

Methods:

Flow Cytometry Analysis

EPCs cells are thought to derive from Sca-1-positive hematopoieticprogenitor cells (Takahashi et al., 1999). The percentage of monuclearcells expressing the EPCs marker protein Sca-1 was then determined byflow cytometry. Seven days after to ischemia, mononuclear cells wereisolated from peripheral blood (300 μl) and from bone marrow of micetreated with either the empty pcDNA3 plasmid or the pcDNA3-mIL18BPplasmid (n=5 per group). Bone marrow cells were obtained by flushing thetibias and femurs. Low density monuclear cells were isolated bydensity-gradient centrifugation with Ficoll. Mononuclear cells were thenincubated with fluorescein isothiocyanate (FITC) conjugated monoclonalantibodies against Sca-1 (D7, BD Pharmingen). Isotype-identicalantibodies served as controls.

EPC Differentiation Assay

Immediately after isolation, 5.10⁶ bone marrow derived monuclear cellswere also plated on 35 mm-cell culture dishes coated with rat plasmavitronectin (Sigma) and gelatin (0.1%) and maintained in endothelialbasal medium (EBM2, Bio whittaker). After 4 days in culture, nonadherentcells were removed and adherent cells underwent immunochemicalsanalysis.

To detect the uptake of1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine-labeledacetylated low-density lipoprotein (AcLDL-Dil), cells were incubatedwith AcLDL-Dil (Tebu) at 37° C. for 1 hour. Cells were then fixed with2% paraformaldehyde, incubated with a primary polyclonal rabbit antibodydirected against and von-Willbrand factor (vWF) (DAKO) for 1 hour, andwith FITC-labeled monoclonal antirabbit IgG (H+L) for 30 min (Coulter).Dual-stained cells positive for both AcLDL-Dil and vWF were judged to beEPCs, and they were counted per well. Three independent investigatorsevaluated the number of EPCs per well by counting three randomlyselected high-power fields. Results are then expressed as percentage oftotal number of mononuclear cells.

Results:

EPCs are thought to derive from Sca-1 positive mononuclear cells(Takahashi et al., 1999). The percentage of Sca-1 positive mononuclearcells in the peripheral blood remained unchanged in IL-18BP-treated micecompared with control animals (31.5±13% versus 28.5±13%, respectively).Similarly, the overall number of Sca-1 positive monuclear cells isolatedfrom bone-marrow did not differ among IL-18BP-treated mice and controlanimals (4.35±0.95% versus 5.87±0.22%, respectively). Furthermore,IL-18BP treatment did not affect the total number of peripheral blood orbone marrow mononuclear cells (data not shown).

EPCs were isolated and cultivated from bone marrow mononuclear cells andcharacterized as dual-stained cells positive for AcLDL-Dil and vWF. Thepercentage of cells with double positive-staining was almostundetectable in non ischemic animals (<5%, n=4). Ischemia induced amarked increase in the percentage of cells with double positive-stainingfor AcLDL-Dil and vWF (48±3%, p<0.001 versus non ischemic animals). Suchan effect was further expanded by IL-18BP treatment (48±3% in controlsversus 85±2% in IL-18BP-treated mice, p<0.001) (FIG. 5). Thus, IL-18BPtreatment seems to stimulate the differentiation of mononuclear cellsinto EPCs rather than increase the number of circulating progenitorcells.

REFERENCES

-   1. Buggemann et al., Eur. J. Immunol. 21:1323-1326 (1991)-   2. DiDonato, J A, Hayakawa, M, Rothwarf, D M, Zandi, E. and    Karin, M. (1997). Nature 388, 16514-16517.-   3. Elliott, M. J., Maini, R. N., Feldmann, M., Long-Fox, A.,    Charles, P., Bijl, H., and Woody, J. N., 1994, Lancet 344,    1125-1127.-   4. Engelmann, H., Novick, D., and Wallach, D., 1990, J. Biol. Chem.    265, 1531-1536.-   5. Grantham (1974), Science, 185.862-864.-   6. Kim S H, Eisenstein M, Reznikov L, Fantuzzi G, Novick D,    Rubinstein M, Dinarello C A. Structural requirements of six    naturally occurring isoforms of the IL-18 binding protein to inhibit    IL-18. Proc Natl Acad Sci USA 2000; 97:1190-1195.-   7. Kim S H et al., J. Immuno. 2001, 166, pp. 148-154.-   8. Knight D M, Trinh H, Le J, Siegel S, Shealy D, McDonough M,    Scallon B, Moore M A, Vilcek J, Daddona P, et al. Construction and    initial characterization of a mouse-human chimeric anti-TNF    antibody. Mol Immunol 1993 Nov. 30:16 1443-53-   9. Maniatis et al., Molecular Cloning: A Laboratory Manual, Cold    Spring Harbor Laboratory, New York, 1982.-   10. Meldrum, D. R., Cleveland, J. C., Jr., Cain, B. S., Meng, X. &    Harken, A. H. (1998) Ann Thorac Surg 65, 439-43.-   11. Mendez, M. M., Green, L. L., Corvalan, J. R. F., Jia X-C.,    Maynard-Currie, E. E., Yang, X-D., Gallo, M. L., Louie, D. M.,    Lee, D. V., Erickson, K. L., Luna, J., Roy, C. M-N., Abderrahim, H.,    Kirshenbaum, F., Noguchi, M., Smith, D. M., Fukushima, A., Hales, J.    F., Finer, M. H., Davis, C. G., Zsebo, K. M. and Jakobovits, A.    (1997). “Functional transplant of megabase human immunoglobulin loci    recapitulates human antibody response in mice”. Nature Genetics, 15,    146-56.-   12. Nakamura, K, Okamura, H, Nagata, K. and Tamura, T. (1989).    Infect. Immun. 57, 590-595.-   13. Novick, D, Kim, S-H, Fantuzzi, G, Reznikov, L, Dinarello, C, and    Rubinstein, M (1999). Immunity 10, 127-136.-   14. Parnet, P, Garka, K E, Bonnert, T P, Dower, S K, and Sims, J E.    (1996), J. Biol. Chem. 271, 3967-3970.-   15. Silvestre, J. S., Mallat Z, Duriez M, Tamarat R, Bureau M F,    Scherman D, Duverger N, Branellec D, Tedgui A, Levy B I. 2000.    Antiangiogenic effect of interleukin-10 in ischemia-induced    angiogenesis in mice hindlimb. Circ. Res. 87: 448-452.-   16. Silvestre, J. S., Mallat Z, Tamarat R, Duriez M, Tedgui A and    Levy B I. 2001. Regulation of Matrix Metalloproteinase activity in    ischemic tissue by interleukin-10: Role in ischemia-induced    angiogenesis. Circ. Res. 89: 259-264.-   17. Takahashi, T., Kalka, C., Masuda, H., Chen, D., Silver, M.,    Kearney, M., Magner, M., Isner, J. M., Asahara, T. 1999. Ischemia-    and cytokine-induced mobilization of bone marrow-derived endothelial    progenitor cells for neovascularization. Nat. Med. 5:434-438.-   18. Torigoe, K., Ushio, S., Okura, T., Kobayashi, S., Taniai, M.,    Kunikate, T., Murakami, T., Sanou, O., Kojima, H., Fuji, M., Ohta,    T., Ikeda, M., Ikegami, H. & Kurimoto, M. (1997) J Biol Chem272,    25737-25742.-   19. Tomizuka et al., Proc. Natl. Acad. Sci. USA 97:722-727 (2000)-   20. Tucci, A., James, H., Chicheportiche, R., Bonnefoy, J. Y.,    Dayer, J. M., and Zubler, R. H., 1992, J. Immunol. 148, 2778-2784.-   21. Yoshimoto T, Takeda, K, Tanaka, T, Ohkusu, K, Kashiwamura, S,    Okamura, H, Akira, S and Nakanishi, K (1998). J. Immunol. 161,    3400-3407.

1. A method for the treatment and/or prevention of peripheral vascular disease in an individual in need thereof comprising administering to the individual an effective inhibiting amount of an IL-18 inhibitor and a pharmaceutically acceptable carrier.
 2. The method according to claim 1, wherein the peripheral vascular disease is peripheral arterial disease.
 3. The method according to claim 1, wherein the peripheral vascular disease is peripheral vascular disease of lower extremities.
 4. The method according to claim 2, wherein the peripheral arterial disease is peripheral vascular disease of lower extremities.
 5. The method of claim 1, wherein the peripheral vascular disease is peripheral ischemia.
 6. The method of claim 5, wherein peripheral ischemia is critical limb ischemia.
 7. The method according to claim 1, wherein the peripheral vascular disease is Buerger's Disease (Thromboangiitis Obliterans).
 8. A method for the treatment and/or prevention of claudication in an individual in need thereof comprising administering to the individual an effective inhibiting amount of an IL-18 inhibitor and a pharmaceutically acceptable carrier.
 9. A method for the prevention and/or treatment of gangrene and/or ulcer in an individual in need thereof comprising administering to the individual an effective inhibiting amount of an IL-18 inhibitor and a pharmaceutically acceptable carrier.
 10. A method for the prevention of limb amputation in an individual in need thereof comprising administering to the individual an effective inhibiting amount of an IL-18 inhibitor and a pharmaceutically acceptable carrier.
 11. The method according to claim 1, wherein the IL-18 inhibitor is selected from the group consisting of inhibitor of caspase-1 (ICE), an antibody against IL-18, an antibody against any of the IL-18 receptor subunits, an inhibitor of the IL-18 signaling pathway, an antagonist of IL-18 which competes with IL-18 and blocks the IL-18 receptor, and an IL-18 binding protein, isoform, mutein, fused protein, functional derivative, active fraction or circularly permutated derivative thereof inhibiting biological activity of IL-18.
 12. The method according to claim 11, wherein the IL-18 inhibitor is an antibody directed against IL-18 receptor α.
 13. The method according to claim 11, wherein the IL-18 inhibitor is an antibody directed against IL-18 receptor β.
 14. The method of claim 11, wherein the antibody is a humanized or human antibody.
 15. The method of claim 12, wherein the antibody is a humanized or human antibody.
 16. The method of claim 13, wherein the antibody is a humanized or human antibody.
 17. The method according to claim 1, wherein the IL-18 inhibitor is an IL-18 binding protein (IL-18BP), or a salt, an isoform, a mutein, a fused protein, a functional derivative, an active fraction or circularly permutated derivative thereof.
 18. The method according to claim 11, wherein the IL-18 inhibitor is glycosylated at least at one site.
 19. The method according to claim 11, wherein the fused protein comprises an immunoglobulin (Ig) fusion.
 20. The method according to claim 11, wherein the functional derivative comprises at least one moiety attached to one or more functional groups, which occur as one or more side chains on the amino acid residues.
 21. The method according to claim 11, wherein the moiety is a polyethylene moiety.
 22. A method of treating and/or preventing peripheral vascular disease in an individual in need thereof comprising administering to the individual an expression vector comprising a coding sequence for an IL-18 inhibitor and a pharmaceutically acceptable carrier.
 23. A method of treating and/or preventing peripheral vascular disease comprising administering to an individual a vector for inducing and/or enhancing the endogenous production of an inhibitor of IL-18 in a cell. 